Besides the fact that lenny hasn't been testing for a long time now, there isn't a X_DIR "x710" in this whole packet thus you don't need to wonder about it is failing all the time with the error:
"cp: cannot stat `/tmp/fglrx-install.1GJKvS/x710_64a/*': No such file or directory"

xserver 1.12.3-1

This was rumored to address the segfaults. Does anyone have experience with this version?